With the shift from ozone layer-depleting chlorofluorocarbons toward refrigerant substitutes in accordance with the Montreal Protocol, much research is being carried out on refrigerating machine oils suitable for such refrigerant substitutes. Refrigerating machine oils used for hydrofluorocarbon (HFC) refrigerants, for example, include synthetic oils such as polyol esters and ethers, which are miscible with HFC refrigerants (for example, see Patent Documents 1-3).    [Patent Document 1] Japanese Patent Public Inspection HEI No. 3-505602    [Patent Document 2] Japanese Unexamined Patent Publication HEI No. 3-128992    [Patent Document 3] Japanese Unexamined Patent Publication HEI No. 3-200895